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Migration mechanisms of interphase boundaries (IPBs) are essential for understanding solid phase transformations. Most studies of the migration mechanisms of IPBs are focused on transformations under rational or near-rational orientation relationships. However, for cases of irrational orientation relationships that widely exist in massive transformations and grain boundary (GB) precipitations, knowledge remains extremely lacking. In this study, taking a triangular-square massive transformation as an example, we explored the migration mechanisms of IPBs with irrational orientation relationships at atomic scales by using the phase-field crystal method. Crystallography analysis based on near-coincidence site calculations also were conducted to verify simulated IPBs structures. Both massive transformations and precipitation transformations were reproduced using the phase-field crystal model. The simulation results show that, similar to the case of rational orientation relationships, the IPBs with irrational orientation relationships migrate by a ledge mechanism due to the satisfying of the edge-to-edge matching relationship. Further simulations on the interactions between IPBs and GBs indicate that GBs can make the newly generated massive phase change its orientation during the process of massive phase transfer across some low-angle GBs.

Branching is a fundamental mechanism for lamellar spacing adjustment during eutectic solidification. However, the kinetic mechanism of branching is still unclear due to the lack of in-situ observations. In this work, utilizing the binary phase-field crystal model, we investigated the lamellar branching process during eutectic directional growth on an atomic scale. By visualizing the new lamella creation process, we found that new α lamellae form from heterogeneous nucleation at the front of the β/liquid interface. After further simulating eutectic solidification with different temperatures and lattice-mismatches, we found that the conditions that promote the heterogeneous nucleation could also stimulate lamellar branching. Conversely, if we suppress the heterogeneous nucleation process, lamellar branching will be hard to emerge, and the eutectic morphology will be a 2λ oscillating pattern.

This work deals with the quantification and application of the modified two-mode phase-field crystal model (M2PFC; Asadi and Asle Zaeem, 2015) for face-centered cubic (FCC) metals at their melting point. The connection of M2PFC model to the classical density functional theory is explained in this article. M2PFC model in its dimensionless form contains three parameters (two independent and one dependent) which are determined using an iterative procedure based on the molecular dynamics and experimental data. The quantification process and computer simulations are performed for Ni and Al as two case studies. The quantitative M2PFC models are used in series of numerical simulations to determine the two-phase FCC-liquid coexisting and the bulk properties at the melting points of Ni and Al. The calculated and predicted properties are the expansion in melting, elastic constants, solid-liquid interface free energy, and surface anisotropy, which are also compared with their available experimental or computational counterparts in the literature.

In this paper we present the application of an anisotropic phase-field crystal model to the process of the heteroepitaxial growth in anisotropic systems. During the growth of the thin films with sheared non-cubic lattice the elastic strain gives rise to dislocations and grain boundaries due to the difference between the film and the substrate lattice in terms of lattice constant (misfit) and lattice shearing (anisotropy difference). The numerical simulations for various misfits and anisotropy difference demonstrate that the anisotropic evolution equation for the phase-field variables allows to simulate the growth of the layers in anisotropic systems. We investigate this phenomenon and derive the relationships for the phenomenological dependencies such as the dependence of the characteristic layer thickness and the number of defects on the misfit for various anisotropy difference based on our recently developed anisotropic phase-field crystal model [28] .

The molecular-dynamics method was used to examine the effect of cross-sectional sample size on detonation processes in molecular crystals. It was shown that, in the molecular crystal model considered, an increase in cross-sectional size has no noticeable effect on the propagation velocity of detonation waves, on the delay time of the chemical reaction, and on the energy macrocharacteristics of the disturbed region. Also, the results of the present molecular-dynamic modeling were compared with the predictions of the continuum theory of detonation. Good agreement between the detonation velocities and between the values of thermodynamic parameters at the Chapman–Jouguet point was obtained.

A mechanism of the phase transition between two modulated structures with different wave vectors was proposed and investigated numerically. The phase transition occurs through the mechanism of nucleation and growth of the new phase. The role of the nucleus is played by an unstable domain wall and the domain of a new low energy phase grows due to the motion of autowaves.